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Full text of "ASTM D2015: Standard Test Method for Gross Calorific Value of Solid Fuel by the Adiabatic Bomb Calorimeter"

*********A********* 





By Authority Of 

THE UNITED STATES OF AMERICA 

Legally Binding Document 



By the Authority Vested By Part 5 of the United States Code § 552(a) and 
Part I of the Code of Regulations § 51 the attached document has been duly 
INCORPORATED BY REFERENCE and shall be considered legally 
binding upon all citizens and residents of the United States of America. 
HEED THIS NOTICE : Criminal penalties may apply for noncompliance. 




Document Name: ASTM D20 1 5 : Standard Test Method for Gross Calorific 

Value of Solid Fuel by the Adiabatic Bomb Calorimeter 

CFR Section(s): 



Standards Body: 




Designation: D 2015 - 96 



Standard Test Method for 

Gross Calorific Value of Coal and Coke by the Adiabatic 

Bomb Calorimeter'' 

This standard is issued under the fixed designation D 2015; the number immediately following the designation indicates the year of 
original adoption or^ in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A 
superscript epsilon (e) indicates an editorial change since the last revision or reapproval. 

This standard has been approved for use by agencies of the Department of Defense. Consult the DoD Index of Specifications and 
Standards for the specific year of issue which has been adopted by the Department of Defense. 



1. Scope 

1 . 1 This test method covers the determination of the gross 
calorific value of coal and coke by the adiabatic bomb 
calorimeter. 

1.2 The values stated in SI units and British thermal units 
are to be regarded as the standard. The values given in 
parentheses are for information only. 

1.3 This standard does not purport to address the safety 
concerns, if any, associated with its use. It is the responsi- 
bility of the user of this standard to establish appropriate 
safety and health practices and determine the applicability of 
regulatory limitations prior to use. For specific hazard 
statements see Section 8. 

1.4 All accountability and quality control aspects of 
Guide D 4621 apply to this standard. 

2. Referenced Documents 

2.1 ASTM Standards: 

D 121 Terminology of Coal and Coke^ 

D 346 Practice for Collection and Preparation of Coke 

Samples for Laboratory Analysis^ 
D 1 193 Specification for Reagent Water^ 
D2013 Method of Preparing Coal Samples for Analysis^ 
D 3173 Test Method for Moisture in the Analysis Sample 

of Coal and Coke^ 
D3177 Test Methods for Total Sulfur in the Analysis 

Sample of Coal and Coke^ 
D 3 1 80 Practice for Calculating Coal and Coke Analyses 
" from As-Determined to DijGFerent Bases^ 
D4239 Test Method for Sulfur in the Analysis Sample of 

Coal and Coke Using High Temperature Tube Furnace 

Combustion Methods^ 
D4621 Guide for Accountability and Quality Control in 

the Coal Analysis Laboratory^ 
E 1 Specification for ASTM Thermometers'^ 
E 144 Practice for Safe Use of Oxygen Combustion 

Bombs^ 



* This test method is under the jurisdiction of ASTM Committee D-5 on Coal 
and Coke and is the direct responsibility of Subcommittee D05.21 on Methods of 
Analysis. 

Current edition approved July 10, 1996. Published September 1996. Originally 
pubhshed as D 20 1 5 - 62 T. Last previous edition D 20 1 5 - 95 . 

2 Annual Book of ASTM Standards, Vol 05.05. 

3 Annual Book of ASTM Standards, Vol 1 1 .0 1 . 
"^AnnualBookofASTM Standards, Vol 14.03. 
^Annual Book ofASTM Standards, Vol 14.02. 



3. Terminology 

3.1 Definitions: 

3.1.1 calorific value, n — the heat produced by combustion 
of a unit quantity of a substance under specified conditions. 

3.1.1.1 Discussion — It is expressed in this test method in 
British thermal units per pound (Btu/lb). Calorific value may 
also be expressed in calories per gram (cal/g) or in the 
International System of Units (SI), joules per gram (J/g), 
when required. The unit equivalents are given in Table 1. 

3.1.2 gross calorific value (gross heat of combustion at 
constant volume) Q^ (grpssj^see Terminology D 121. 

3.1.3 net calorific value (net heat of combustion at con- 
stant pressure) Qp (net) — see Terminology D 121. 

3.1.4 calorimeter— as used in this test method, consists of 
the bomb and its contents, the calorimeter vessel (bucket) 
with stirrer, the water in which the bomb is immersed, and 
the portions of the thermometer and the ignition leads 
within the calorimeter vessel. 

3.2 Descriptions of Terms Specific to This Standard: 

3.2. 1 corrected temperature me— the temperature change 
of the calorimeter caused by the process that occurs inside 
the bomb, that is, the observed temperature change corrected 
for various effects as noted in 10.4. 1 . 

Note 1 — rTemperature is measured in either degrees Celsius or 
degrees Fahrenheit, Thermometer corrections should be applied. Tem- 
peratures may be recorded in ohms or other arbitrary units instead of 
degrees. Consistent units must be used in standardization and the actual 
calorific . value determination. If . arbitrary units other than degrees 
Celsius or Fahrenheit are used, the temperature interval over which all 
tests are made, must not vary so much that an error greater than 0.00 rC 
would be caused. 

3.2.2 energy equivalent^ heat capacity, or water equiva- 
lent— Xht energy required to raise the temperature of the 
calorimeter one arbitrary unit. This is the quantity that, 
when multiplied by the corrected temperature rise, then 
adjusted for extraneous heat effects, and divided by the mass 
of the sample, gives the gross calorific value. 

Note 2 — Energy units for quantities listed throughout ' this test 
method are such that the number of energy units per gram of sample 
corresponds exactly to the number of British thermal units per pound of 
sample. For brevity these are referred to as British thermal units. The 
actual energies are smaller than those stated by the ratio of the number 
of pounds per gram (1/453.59), The energy equivalent of the calorimeter 
has the units (British thermal units per pound) times (grams per degree). 
Conversion to other units is discussed in Appendix XI. 2. Time is 
expressed in minutes. Mass is expressed in grams. 

4. Summary of Test Method 

4.1 Calorific value is determined in this test method by 



253 



# D 2015 



TABLE 1 Calorific Value 



1 Btu = 1055.06 J 
1 Calorie^ = 4.1868 J 



1 Btu/lb = 2.326 J/g 
1.8Btu/lb = 1.0cal/g 



^ international tables calorie. 

burning a weighed sample, in oxygen, in a calibrated 
adiabatic bomb calorimeter under controlled conditions. 
The calorimeter is standardized by burning benzoic acid. 
The calorific value of the sample is computed from temper- 
ature observations made before, during and after combus- 
tion, making proper allowances for heat contributed by other 
processes, and for thermometer and thermochemical correc- 
tions. 

Note 3 — Oxidation after sampling of susceptible low-rank coal or 
lignite may result in a reduction of calorific value. Unnecessary exposure 
of the sample to air from the time of sampling or delay in analysis shall 
be avoided. 

5. Significance and Use 

5.1 Thp gross calorific value is used to compute the total 
calorific content of the quantity of coal represented by the 
sample for payment purposes, provided the buyer and the 
seller mutually agree upon this. 

5.2 The gross calorific value is used in computing the 
calorific value versus sulfur content to determine if the coal 
meets regulatory requirements for industrial fuels. 

5.3 The gross calorific value may be used for evaluating 
the effectiveness of beneficiation processes, or for research 
purposes. 

6. Apparatus and Facilities 

6.1 Test Space, shall be a room or area free from drafts 
and that can be kept at a reasonably uniform temperature for 
the time required for the determination. The apparatus 
should be shielded from direct sunUght and radiation from 
other heat sources. Thermostatic control of room tempera- 
ture and controlled relative humidity are desirable. 

6.2 Combustion Bomb, shall be constructed of materials 
that are not affected by the combustion process or products 
sufficiently to introduce measurable heat input or alteration 
of end products. The bomb must be designed so that all 
liquid combustion products can be completely recovered by 
washing the inner surfaces. There must be no gas leakage 
during a test. The bomb must be capable of withstanding a 
hydrostatic pressure test of 20 MPa (3000 psig) at room 
temperature without stressing any part beyond its elastic 
limit. 

6.3 Balance, shaH be a laboratory balance having capa- 
biUty to weigh the sample t6 the^ nearest 0.0001 g. The 
balance should be checked periodically to determine is 
accuracy. 

6 A Calorimeter Vessel, shall be made of metal with a 
tarnish-resistant coating, and with all outer surfaces highly 
polished. Its size shall be such that the bomb will be 
completely immersed in water when the calorimeter is 
asseinbled. It shall have a device for stirring the water 
thoroughly and at ,a uniform rate, but with minimum heat 
input. Continuous stirring for 10 min shall not raise the 
calorimeter temperature more than 0.0 TC (0.02T) starting 
with identical temperatures in the calorimeter, rbom, and 
jacket. The immersed portion of the stirrer shall be coupled 



to the outside through a material of low-heat conductivity. 

6.5 Jacket, shall be a double-walied, water-filled jacket 
fully enclosing the calorimeter. The sides, top, and bottom of 
the calorimeter vessel shall be approximately 10 mm from 
the inner wall of the jacket to hiinimize convection currents. 
Mechanical supports for the calorimeter vessel shall provide 
as little thermsd conduction as possible. The jacket shall have 
a device for stirring the water thoroughly and at a uniform 

^ rate with minimum heat input. 

6.6 Thermometers, used to measure temperature in the 
calorimeter and jacket shall be any of the following types or 
combinations thereof: 

6.6.1 Liquid-in-Glass Thermometers, conforming to the 
requirements for ASTM Thermometers 56C, 56F, II 6C, or 
117C as prescribed in Specification E 1. The thermometers 
shall be tested for accuracy against a known standard 
(preferably by the 'National Institute of Standards and 
Technology). For Thermometers 56C and 56F the caUbra- 
tion should be at intervals no larger than 2.0'C or 2.5°F over 
the entire graduated scale". The maximum difference in 
correction between any two test points shall be no more than 
0.02'C or 0.05T. For Thermometers 116C and 117C, the 
calibration should be at intervals no larger than 0.5^0 over 
the entire calibrated range. The maximum difference in 
correction between any two test points shall not be more 
than 0.02'C. 

6.6.2 Beckman Differential. Thermometer, (glass enclosed 
scale, adjustable), having a range of approximately 6T in 
0.0 rC subdivisions reading upward and conforming to the 
requirements for Thermometer 1 15C, as prescribed in Spec- 
ification E 1, may be used. Each of these thermometers shall 
be tested for accuracy against a known standard (preferably 
by the National Institute of Standards and Technology) at 
intervals no larger than TC ovet the entire graduated scale. 
The maximum difference in the correction between any two 
test points shall not be more than 0.02°C. 

6.6.3 Other Thermometers, of an accuracy equal to or 
better than 0.00 TC, such as platinum resistance or hnear 
thermistors are preferred if f)roperly calibrated. A 
Wheatstone bridge and galvanometer capable of measuring 
resistance to 0.0001 Q are necessary for use with 25-0 
platinum resistance thermometers. 

6.7 Thermometer Accessories — A magnifier is required 
for reading liquid-in-glass thermometers to one tenth of the 
smallest scale division. This shall &ave a lens and holder 
designed so as to introduce no significant errors due to 
parallax. 

6.8 Sample Holder, shall be an open crucible of platinum, 
quartz, or acceptable base-metal alloy. Base-metal alloy 
crucibles are acceptable, if after a few preliminary firings, the 
weight does not change significantly between tests. 

6.9 Ignition Wire, shall be 100 mm of 0.16 mm diameter 
(No. 34 B & S gage) nickel-chromium (Chromel C) alloy or 
iron wire. Platinum or palladium wire, 0.10 mm diameter 
(No. 38 B & S gage), may be used, provided constant ignition 
energy is supplied. The length, or niass, of the ignition wire 
shall remain constant for all calibrations and calorific value 
determinations. 

6.10 Ignition Circuit, for ignitipn purposes shall provide 6 
to 16 V alternating or direct current to the ignition wire. An 
ammeter or pilot light is required in the circuit to indicate 



254 



# D2015 



when current is flowing. A step-down transformer, con- 
nected to an alternating current lighting circuit or batteries, 
maybe used. 

6.1 1 Buret, used for the acid titration shall have 0.1-mL 
divisions. 

6.12 Automated Controller and Temperature Measuring 
Accessories, may be used. 

7. Reagents 

7.1 Purity of Reagents — Reagent grade chemicals shall be 
used in all tests. Unless otherwise indicated, it is intended 
that all reagents shall conform to the specifications of the 
Committee on Analytical Reagents of the American Chem- 
ical Society where such specifications are available.^ Other 
grades may be used, provided it is first ascertained that the 
reagent is of sufficiently high purity to permit its use without 
lessening the accuracy of the determination. 

7.2 Reagent Water — Reagent water conforming to Type 
II of Specification D 1193, shall be used for preparation of 
reagents and washing of the bomb interior. 

7.3 Benzoic Acid, (CeHsCOOH), shall be the National 
Institute of Standards and Technology benzoic acid. The 
crystals shall be pelleted before use. Commercially prepared 
pellets may be used provided they are made from National 
Institute of Standards and Technology benzoic acid. The 
value of heat of combustion of benzoic acid for use in the 
calibration calculations shall be in accordance with the value 
listed in the National Institute of Standards and Technology 
certificate issued with the standard. 

7.4 Methyl Orange, Methyl Red, or Methyl Purple Indi- 
cator, may be used to titrate the acid formed during 
combustion. The indicator used shall be the same for both 
calibration and calorific value determinations. 

7.5 Oxygen, shall be free of combustible matter. Only 
oxygen manufactured from liquid air, guaranteed to be 
greater than 99.5 % pure, should be used. Oxygen made by 
the electrolytic process may contain a small amount of 
hydrogen rendering it unfit without purification. 

7.6 Sodium Carbonate Standard Solution, (NasCOg), 
should be dried for 24 h at 105°C. Dissolve 20.9 g in water 
and dilute to 1 L. One millihtre of this solution is equivalent 
to 10.0 Btu in the nitric acid (HNO3) titration. 

8. Hazards 

8.1 The following precautions are recommended for safe 
calorimeter operation. Additional precautions are given in 
Practice E 144. Also consult the calorimeter manufacturer's 
installation and operating manuals before using the calorim- 
eter. 

8.2 The mass of coal or coke sample and the pressure of 
the oxygen admitted to the bomb must not exceed the 
manufacturer's recommendations. 

8.3 Inspect the bomb parts carefully after each use. Check 
the bomb for thread wear on any closures; if an inspection 



^Reagent Chemicals, American Chemical Society Specifications, American 
Chemical Society, Washington, DC. For suggestions on the testing of reagents not 
listed by the American Chemical Society, see Analar Standards for Laboratory 
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia 
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), 
Rockville, MD. 



reveals any wear, replace the worn parts or return the bomb 
to the factory for testing or replacement of the defective 
parts. It is good practice to replace the o-rings and seals, 
inspect screw cap threads, and hydrostatically test the bomb 
as per the manufacturer's recommendations. 

8.4 The oxygen supply cyUnder should be equipped with 
an approved type of safety device, such as a reducing valve, 
in addition to the needle valve and pressure gage used in 
regulating the oxygen feed to the bomb. Valves, gages, and 
gaskets must meet industry safety code. Suitable reducing 
valves and adaptors for 3 to 4-MPa (300 to 500-psi) 
discharge pressure are obtainable from commercial sources 
of compressed gas equipment. The pressure gage shall be 
checked periodically for accuracy. 

8.5 During ignition of a sample, the operator must not 
permit any portion of her or his body to extend over the 
calorimeter. 

8.6 When combustion aids are employed, extreme cau- 
tion must be exercised not to exceed the bomb manufactur- 
er's recommendations and to avoid damage to the bomb. Do 
not fire loose fluffy material such as unpelleted benzoic acid, 
unless thoroughly mixed with the coal sample. 

8.7 Do not fire the bomb if the bomb has been dropped or 
turned over after loading, or if there is evidence of a gas leak 
when the bomb is submerged in the calorimeter water. 

8.8 For manually operated calorimeters, the ignition cir- 
cuit switch shall be of the momentary double-contact type, 
normally open, except when held closed by the operator. The 
switch should be depressed only long enough to fire the 
charge. 

9. Sample 

9.1 The sample shall be the material pulverized to pass a 
250-|am (No. 60) sieve, prepared in accordance with either 
Practice D 346 for coke, or Method D 2013 for coal. 

9.2 A separate portion of the analysis sample should be 
analyzed simultaneously for moisture content in accordance 
with Method D2013 and Test Method D3173, so that 
calculation to other bases can be made. 

9.3 Sulfur analysis shall be made in accordance with Test 
Methods D 3177. 

10. Standardization 

10.1 The calorimeter is standardized by combustion of 
benzoic acid. 

10.2 Determine the energy equivalent as the average of a 
series of ten individual test runs. To be acceptable the 
relative standard deviation of the series shall be 0.15 % or 
less of the average energy equivalent (see Table 2). For this 
purpose, any individual test may be discarded if there is 
evidence of incomplete combustion. If, after considering the 
possibility of outliers utiUzing criterion established in Prac- 
tice E 178, this limit is not met, one should review operation 
of the calorimeter for any assignable cause which should be 
corrected before repeating the series. 

10.3 Procedure: 

10.3.1 Regulate the weights of the pellets of benzoic acid 
in each series to yield approximately the same temperature 
rise as that obtained with the coal tested in the same 
laboratory. The usual range of masses is 0.9 to 1.3 g. Weigh 



255 



# D2015 



TABLE 2 Standard Deviations for Calorimeter Standardization^ 





Column A 


Column B 




Column C 


Number Energy Equivalent 
(Btu/lb) X (g/^C) 


Code to 4400 
(Column A - 4400) 


(Column 8)2 


1 


4412 


12 




144 


2 


4407 


7 




49 


3 


4415 


15 




225 


4 


4408 


8 




64 


5 


4404 


4 




16 


6 


4406 


6 




36 


7 


4409 


9 




81 


8 


4410 


10 




100 


9 


4412 


12 




144 


10 


4409 


9 




81 


SUM 




92 




940 


Average = X = 


:2X/10 = (92/10) + 4400 


- 4409 






Variance = s^ 


S Column C - p Colu 
n- 1 


imn Bf/n] 940 - 
'10.4 = 3.22 


r(92) 

9 


"'°^ = WA 


Standard deviation = s = Vvariance = V 





^ In this example tlie values of energy equivalent are typical for a calorimeter 
calibrated so that, if the energy equivalent Is hfiuitiplied by the temperature rise In 
degrees Celsius per gram of sample, the calorific value of the sample will be 
obtained in British Thermal units per pound.' 

the pellet to the nearest 0.0001 g in the sample holdei" in 
which it is to be burned, and record the weight as the mass. 

10.3.2 Rinse the bomb, invert to drain, and leave undried. 
Add 1.0 mL of water to the bomb prior to assembly for a 
determination. 

10.3.3 Connect a measured length of ignition wire to the 
ignition terminals, with enough slack to allow the ignition 
wire to maintain contact with the sample. 

10.3.4 Assemble the bomb and charge it with oxygen to a 
consistent pressure between 2 to 3 MPa (20 to 30 atm). This 
pressure must remain the same for each calibration and each 
calorific-value determination. Admit the oxygen slowly into 
the bomb so as not to blow powdered material from the 
sample holder. If the pressuire exceeds the specified pressure, 
do not proceed with the combustion. liistead, detach the 
fiUing connection, exhaust the bomb in the usual manner, 
and discard the sample. 

10.3.5 Fill the calorimeter vessel (bucket) with the mea- 
sured (or weighed) quantity of water adjusted from 1.0 to 
2.0°C (2.0 to 4.0**?) below room temperature, but not lower 
than 20'*C (68T). Use the same mass of water in each test 
weighed to +0.5 g. For 2000-mL calorimeters, the proper 
quantity can be obtained by use of a volumetric flask 
cahbrated to deliver 2000 ±0.5 mL. As the density of water 
varies with temperature, make suitable corrections if the 
water temperature varies from the temperature at which the 
flask was calibrated. Place the assembled bomb in the 
calorimeter vessel. Check that no oxygen bubbles are leaking 
from the bomb. Place the calorimeter vessel in the jacket; 
connect the electrodes; place the stirrers, thermometers, and 
cover in position. Start the stirrers and contiriue to operate 
them throughout the determination. Examine the thermom- 
eters for Uquid separation and correct any separation before 
proceeding. The starting^ temperature should be within 
±0.5''C (0.9T) of that used in analysis of fcoal or coke 
samples. 

Note 4 — Check all liquid-in-glass thennometers at least daily for 
defects, for example, cracked glass, etc. 

10i3.6 Allow 5 min for attainment of equilibrium. Adjust 



the jacket temperature to match the calorimeter temperature 
within 0.0 rC (0.02T) and maintain for 3 min. Use a 
magnifier when using ASTM Bomb Calorimeter Thermom- 
eters 56C or 56F, and estimate all readings (except those 
during the rapid-rise period) to the nearest O.OOS'^C or 
0.005T. Estimate ASTM Thermometers 115C, 116C, or 
1 17C readings to 0.00 TC, and 25 Q resistance thermometer 
readings to the nearest 0.0001 0. Tap mercury thermometers 
(for instance, with a pencil) just before reading to avoid 
errors caused by mercury sticking to the walls of the 
capillary. Take calorimeter temperature readings at one- 
minute intervals until the same temperature, within one- 
tenth of the smallest thermometer subdivision, is observed in 
three successive readings. Record this "initial temperature", 
ti, 20°C (68''F) or higher, to within one-tenth of the smallest 
thermometer subdivision and ignite the charge. Adjust the 
jacket temperature to match the catlorimeter temperature 
during the period of rise; keep the two temperatures as nearly 
equal as possible during the rapid rise and adjust to within 
0.0 rc (0.02T) when approaching the final equihbrium 
temperature. Take calorimeter temperature readings at 1- 
min intervals until the same temperature, within one-tenth 
of the smallest thermometer subdivision, is observed in three 
successive readings. Record this as the "final temperature", 

10.3.7 Open the cover and remove the bomb. Release the 
pressure at a uniform rate, such that the operation will 
require not less than 1 min. Open the bomb and examine the 
bomb interior. Discard the test if unbumed sample or sooty 
deposits are found. Wash the interior of the bomb with 
distilled water containing the titration indicator, until the 
washings are free of acid, and titrate the washings with 
standard sodium carbonate solution. 

10.3.8 Remove and measure, or weigh, the combined 
pieces of unbumed ignition (firing) wire and subtract from 
the original length, or weigh to determine the wire consumed 
in firing. If the wire is weighed, remove the ball of oxidized 
metal from the end of each piece of wire before weighing. 

10.4 Calculations: 

10.4.1 Temperature Rise — Using data obtained as pre- 
scribed in 10.3.6, compute the corrected temperature rise, t, 
as follows: 



^ = ry-r, + Q+C, 



(1) 



where: 

t = 

if = 



corrected temperature rise, "C or °F, 
initial temperature reading at time of firing, °C or °F, 
final temperature reading, °C or °F, 
thermometer emergent stem correction, if required 
(see Note 5 and Annex A 1.1.4), and 
Cs ~ thermometer setting correction, if required (see Note 
5 and Annex A 1.1. 3). 

Note 5 — With all mercury-in-glass thermometers, it is necessary to 
make corrections if the total calorific value is altered by 5.0 Btu or more. 
This represents a change of 0.00 TC or 0.002T in a calorimeter using 
approximately 2000 g of water. Beckmann thermometers also require a 
setting correction and an emergent stem correction (see Annex A 1.1.3 
and A 1.1. 4). Solid-stem ASTM Thermometers 56C and 56F do not 
require emergent stem corrections if all tests, including standardization, 
are performed within the same 5.5°C {WF) interval. If operating 
temperatures range beyond this limit, a differential emergent stem 
correction (see Annex A 1.1.4) must be applied to the corrected 
temperature rise, t, in all tests including standardization. 



256 



# D2015 



10.4.2 Thermochemical Corrections (see Appendix XLl, 
XI. 2, and XI. 3) — Compute the following for each test: 

^1 = correction for the heat of formation of HNO3, Btu. 

Each miliilitre of standard NasCOa is equivalent to 

10.0 Btu, and 

€2 = correction for heat of combustion of firing wire, Btu 

(Note 6). 

= 0.41 Btu/mm or 2.6 Btu/mg for No. 34 B & S gage 

Chromel C wire. 
= 0.49 Btu/mm or 3.2 Btu/mg for No. 34 B & S gage 
iron wire. 
Note 6 — There is no correction for platinum wire provided the 
ignition energy is constant. 

10.4.3 Compute the calorimeter energy equivalent, E, by 
substituting in the following: 



TABLE 3 Summary of Numerical Requirements 

Note— Test values exceeding table limits require additional runs/ 



E^[iHg) + e,'\~e2]/t 



(2) 



where: 
E = 
H = 



calorimeter energy equivalent (Note 7), 
heat of combustion of benzoic acid, as stated in the 
National Institute of Standards and Technology 
Certificate, Btu/lb in air, 

g = mass (weight in air) of benzoic acid, g, 

ei = titration correction (10.4.2), 

€2 ~ fuse wire correction (10.4.2), and 

t = corrected temperature rise. 

Note 7— Using the units and corrections as given in 10.4,1 and 
10.4.2, the energy equivalent of the calorimeter is such that the calorific 
value of the coal sample will be obtained directly in British thermal units 
per pound when the mass of sample is taken in grams. The units of the 
energy equivalent are therefore: (British thermal units per pound) times 
(grams per degree). . . 

10.5 Repeat the procedure for a total of ten deter- 
minations. Compute the standard deviation as illustrated in 
Tablel . 

11. Restandardization 

11.1 Make checks on the energy equivalent value after 
changing the oxygen supply, after changing any part of the 
calorimeter, and at least once a month otherwise. 

11.1.1 If a single new determination differs from the old 
value by 6 Btu/'C (4 Btu/T), the old standard is suspect, 
thereby requiring a second test. 

11.1.2 The difference between the two new determina- 
tions must not exceed 8 Btu/°C (5 Btu/T), and the average of 
the two new determinations must not differ from the old 
standard by more than 4 Btu/^C (3 Btu/T). If these re- 
quirements are met, do not change the calorimeter standard. 

11.1.3 If the requirements given in 11.1.2 are not met, 
two more determinations must be run. The range of the four 
values must not exceed 14 Btu/°C (8 Btu/T), and the average: 
of the four new determinations must not differ from the old 
standard value by more than 3 Btu/'C (2 Btu/T). If these 
requirements are met, do not change the calorimeter staur 
dard., - 

11.1.4 If the requirements given in 11.1.3 are not met, a 
fifth and sixth determination must be run. The range of the 
six new values must not exceed 17 Btu/'C (10 Btu/T), and 
the average of the six new values must not differ from the old, 
standard value by more than 2 Btu/°C (2 Btu/T). If these re- 
quirements are met, do not change the calorimeter standard. 



Number of Runs 



Maximum Range of Results 



MaximumJDiffereiice 
between X^ and Xg^ 





Btu/^'C 


Btu/«F 


Btu/°C 


Btu/°F 


1 






±6 


±4 


2 


8 


5 


±4 


±3 


4 


14 


8 


±3 


±2 


6 


17 


10 


±2 


±2 


10 


20 


12 


±1 


±1 



'^ Values in this table have been rounded off after statistical calculation, and are 
therefore not precisely in a ratio from 1 .8_to 1 .0. 

^ ^1 = average of original standard. Xg = average of check runs. 

11.1.5 If the requirements given in 11.1.4 are not met, 
four more determinations must be run to complete a series 
often runs. The range of these ten results must not exceed 20 
Btu/°C (12 Btu/T), and the average of the ten new standards 
must not differ from the old standard by more than 1 Btu/°C 
(1 Btu/T). If these requirements are met, do not change the 
calorimeter standard. 

11.1.6 If the requirements given in 1 1 . 1 !5 are not met, the 
average value from the ten new values must be used for the. 
new standard energy equivalent, provided that the standard 
deviation of the series does not exceed 6.5 Btu/°C (3.6 
Btu/T). 

1 1.2 The summary of the numerical requirements at each 
stage of restandardization is given in Table 3. 

12, Procedure for Goal and Coke Samples (Note 8) 

12.1 Thoroughly mix the analysis sample of coal or coke 
in the sample bottle and carefully weigh approximately 1 g of 
it into the sample holder. Weigh the sample to the nearest 
0.0001 g. Make each determination in accordance with the 
procedure described in 10.3.2 through 10.3.8. 

Note 8— For anthracite, coke, and coal of high ash content, that do 
not readily bum completely, one of the following procedures are 
recommended: (7) The inside of the sample holder is lined completely 
with ignited asbestos in a thin layer pressed well down in the angles, and 
the sample is then sprinkled evenly over the surface of the asbestos. 
(2) The mass of the sample may be varied to obtain good ignition. If the 
mass is varied, it will be necessary to recalibrate the calorimeter so that 
the water equivalent will be based on the same temperature rise as that 
obtained with the sample weight. (3) A known amount of benzoic acid 
may be mixed with the sample. Proper allowance must be made for the 
heat of combustion of benzoic acid when determining the calorific value 
of the sample. 

Note 9— For the calorific value of coke, it is necessary to use 3-MPa 
(30-atm) pressure for both standardization and analysis. 

12.2 Determine the sulfur content of the sample by any of 
the procedures described in Test Methods D 3177. 

13. Calculation (Note 2) 

13.1 Compute the corrected temperature rise, t, as shown 
in 10.4.1. 

13.2 Thermochemical Corrections (Appendix XI) — Com- 
pute the following for each test: 

correction for the heat of formation of HNO3, Btu. 
Each miliilitre of standard sodium carbonate is equiv- 
alent to 10.0 Btu, 

correction for heat of combustion of ignition wire, Btu, 
0.41 Btu/mm or 2.6 Btu/mg for No. 34 B & S gage. 
Chromel C wire, 



e^ = 



^2 = 



257 



# D 2015 



= 0.49 Btu/mm or 3.2 Btu/mg for No. 34 B & S gage 

iron wire, and 
^3 = correction for difference between heat of formation of 

H2SO4 from the heat of formation of HNO3, Btu, 
= 23.7 times percent of sulfur in sample times mass of 

sample, g. 

14. Calorific Value (Note 10) 

14.1 Gross Calorific Value — Calculate the gross calorific 
value (gross heat of combustion at constant volume), Q^ 
(gross), as follows: 

Q^ (gross) = [{tE) - ei - ^2 - e^]lg (3) 

where: 

Qy (gross) - gross calorific value, Btu/lb, 

/ = corrected temperature rise calculated in 13.1, 

^'G or T, 

E — energy equivalent calculated in 10.4.3, 

^u ^25 ^3 ~ corrections as prescribed in 13.2, and 

g = mass of sample, g. 

Note 10 — This calculation gives calorific value in British thermal 
units per pound. To obtain calorific value in joules per gram, see 
Appendix X2. 

14.2 Net Calorific Value — Calculate the net calorific value 
(net heat of combustion at a constant pressure), Qp (net), as 
follows: 

Qp (net),, = a (gross),, - 5.72 {H,, x 9) (4) 

where: 

Qp (net)o;. === net calorific value at constant pressure, cal/g 

Qy (gross)^, " gross calorific value at constant volume, 
as-received basis, cal/g, and 

Har = total hydrogen as-received basis, where hy- 

drogen includes the hydrogen in sample 
moisture, %. 

Note U — Example for converting from the as-determined (air- 
dried) sample basis to the as-received net caloriQc value basis:"^ 

Galories, as determined (gram/Cal^^) = 7506 

Calories, as received (gram/Calo,) = 7056 

Moisture, as determined (^arf) =2.13 

Moisture, as received (M^^) = 8.00 

Hydrogen, as determined (Had} ~ 5.00 
To convert H^d to Har- 

Har =[(ff ^-0.1119 Ar.^)x }gg"^^^ 

= [(5.00-0.1119x2.13) 

Har = 5.37 

Qp (net)^,= 7056 - 5.72 (5.37 x 9) 
= 7056 - 276 

= 6780 cal/g (International Table Calories) 
= 12204 Btu/lb 
= 28390 J/g 
- 28.39 MJ/kg 

15. Report 

15.1 The results of the calorific value may be reported on 
any of a number of bases, differing from each other in the 



rioo-8, 



+ 0.11 19 M., 



/lOO-S.OOV 
^\100-2.13/ 



-H 0.1119x8.00 



manner that moisture is treated. 

15.2 Use the percent moisture in the sample passing a 
250-iam (No. 60) sieve (Test Method D 3173) to calculate the 
results of the analysis sample to a dry basis; 

15.3 Procedures for converting the value obtained on the 
analysis sample to other bases are described in Practice 
D3180. 



16. Precision and Bias 

16. 1 Precision--T-The relative precision of this test method 
for the determination of gross calorific value (Btu) covers the 
range from 7,1 12 to 8,120 cal/g (12,700 to 14,500 Btu/lb) for 
bituminous coals and from 4,922 to 7,140 cal/g (8,790 to 
12,750 Btu/lb) for subbituminous and lignite coals. 

16.1.1 Repeatability — ^The difference in absolute value 
between two consecutive test results, carried out on the same 
sample of 250-|im (No. 60) pulp, in the same laboratory, by 
the same operator, using the same apparatus, should not 
exceed the repeatability interval for more than 5 % of such 
paired values (95 % confidence level). When such a differ- 
ence is found to exceed the repeatabiUty interval, there is 
reason to question one, or both, of the test results. The 
repeatability interval for this test method is 28 cal/g (50 
Btu/lb) on a dry basis. 

16.1.2 Repeatability — The difference in absolute value 
between test results, obtained in the same laboratory, by the 
same operator, using the same riffle, determined on a single 
test specimen of two separate 2.36-mm (No. 8) test units of 
coal reduced entirely to 250-|j,m (No. 60) and prepared from 
the same bulk sample should not exceed the repeatability 
limit for more than 5 % of such paired values (95 % 
confidence level). When such a difference is found to exceed 
the repeatabihty limit, there is reason to question one, or 
both, of the test results. The repeatabihty Umit for this test 
method on a dry basis is: 



Bituminous coals 
Subbituminous and lignite coals 



39 cal/g (69 Btu/lb) 
33 cal/g (59 Btu/lb) 



"7 For a comprehensive theoretical derivation of calculations for converting 
gross calorific value at constant volume to net calorific value at constant pressure, 
request Research Report RR: D05-1014. 



16.1.3 Reproducibility — The difference in absolute value 
of rephcate determinations, carried out in different laborato- 
ries on representative 250-|im (No. 60) samples, prepared 
from the same bulk sample after the last stage of reduction, 
should not exceed the reproducibility interval for more than 
5 % of such paired values (95 % confidence level). When 
such a difference is found to exceed the reproducibility 
interval, there is reason to question one, or both, of the test 
results. The reproducibility interval for this test method is 56 
cal/g (100 Btu/lb) on a dry basis. 

16.1.4 Reproducibility — The difference in absolute value 
between test results obtained in different laboratories calcu- 
lated as the average of determinations on single test speci- 
mens of two separate 2.36-mm (No. 8) test units of coal 
reduced entirely to 250-|im (No. 60) and prepared from the 
same bulk sample, should not exceed the reproducibility 
hmit for more than 5 % of such paired values (95 % 
confidence level). When such a difference is found to exceed 
the reproducibiUty Umit, there is reason to question one, or 
both, of the test results. The reproducibility limit for this test 
method on a dry basis is: 



Bituminous coals 
Subbituminous and lignite coals 



60 cal/g (107 Btu/lb) 
78 cal/g (140 Btu/lb) 



258 



il^ D 2015 



Note 7— Supporting data for 2.36-mm (No. 8) coal has been filed at Standardized with a compound having a known heat of 



ASTM Headquarters and may be obtained by requesting RR:D05 
1015, 

Note 8— The precision for 250-^im (No. 60) coal is currently being 
evaluated, 

16.2 Bias — The equipment used in this test method for 
measuring gross calorific value has no bias because it is. 



combustion. This procedure may involve tests that produce 
varying levels of heat formation not accounted for in 
standardization. If the thermochemical corrections for heat 
of formation are not done correctly, a bias may be present in 
the determination. 



ANNEX 



(Mandatory Information) 



Al. THERMOMETRIG CORRECTIONS 



Al.l Thermometer Corrections 

Al.1.1 It is necessary to make the following individual 
corrections, if not making the correction would result in an 
equivalent change of 5.0 Btu or more. 

A 1.1. 2 Calibration Correction shall be made in accor- 
dance with the calibration certificate furnished by the 
calibration authority. 

A 1.1. 3 Setting Correction is necessary for the Beckmann 
thermometer. It shall be made in accordance with the 
directions furnished by the calibration authority. 

A 1.1. 4 Differential Emergent Stem Correction — The cal- 
culation of differential stem correction depends upon the 
way the thermometer was cahbrated and how it was used. 
Two conditions are possible: 

Kl AAA Thermometers Calibrated in Total Immersion 
and Used in Partial Immersion— T\As emergent stem correc- 
tion is made as follows: 

Correction = C^ = K {tf- t,) {tj-\- 1^- L-T) (Al.l) 

where: 

Q = emergent stem correction, 

K = 0.00016 for thermometers calibrated in °C, 

= 0.0009 for thermometers cahbrated iii T,, 

L = scale reading to which the thermometer was immersed, 

T = mean temperature of emergent stem, "^C or T, • 

ti = initial temperature reading, ''C or T, and, 

tf — final temperature reading, ^'C or T. 



Note Al.l — Example: Assume the point L, to which the thermonti- 
eter was immersed was \6°C\ its initial reading, tf, was 24.127''C, its final 
reading, t^ was 27.876, the mean temperature of the emergent stem, T 
was 26''C; then: 

Differential stem correction, Q 
= 0.00016 (28 - 24) (28 + 24 - 16 - 26) 
= + 0.0064'*C. 

A 1.1.4.2 Thermometers Calibrated and Used in Partial 
Immersion, but at a Different Temperature than the Calibra- 
tion Temperature — This emergent stem correction is made 
as follows: 



Correction = C^ ==^K(tj;~,t,) (t^ - t^) 



(A1.2) 



where: • 

Cq = emergent stem correction, . 
K = 0.00016 for thermometers calibrated in °C, 
= 0.00009 for thermometers cahbrated in T, 
ti = initial temperature reading, ^C or T, 
tf = final temperature reading, "C or T, 
t^ = observed stem temperature, °C or T, and 
tc = stem temperature at which the thermometer was 
calibrated, °C or T. 
Note A1.2—£':^am;7/e- Assume the initial reading, ?,-, was SOT, the 
final reading, tf, was 86^, and that the observed stem temperature, /o» 
was 82T, and calibration temperature, t^, was 72T then: 

Differential stem correction 
= 0.00009 (86 - 80) (82 - 72) 
= 0.005T 



259 



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APPENDIXES 



(Nonmandatory Information) 



XI. THERMOCHEMICAL CORRECTIONS 



XI. 1 Energy of Formation of Nitric Acid — A correction, 
ei, (10.4.2 and 13.2), is applied for the acid titration. This 
correction is based on the assumptions (I) that all the acid 
titrated is HNO3 formed by the following reaction: 1/2 N2 
(gas) + 5/4 O2 (gas) + 1/2 H2O (liquid) = HNO3 (in 500 mol 
H2O), and (2) that the energy of formation of HNO3 in 
approximately 500 mol of water under bomb conditions is 
-59.0 kJ/mol.s 

X 1 . 1 . 1 A convenient concentration of Na2C03 is 0.394 A'" 
(20.9 g NasCOg/lOOO mL) which gives e^ = 10 times V, 
where V is the volume of Na2C03 in millilitres. The factor 
10.0 (0.394 X 59.0 = 2.326) is to be used for calculating 
calorific value in British thermal units per pound. For other 
units see Table X2.1. When H2SO4 is also present, a part of 
the correction for H2SO4 is contained in the e^ correction 
and remainder in the ^3 correction. 

X 1 .2 Energy of Formation of Sulfuric Acid — By definition 
(see Terminology D 121) the gross calorific value is obtained 
when the product of the combustion of sulfur in the sample 
is SO4 (in grams). However, in actual bomb combustion 
process, all the sulfur is found as H2SO4 in the bomb 
washings. A correction, e^ (see 13.2) is applied for the sulfur 
that is converted to H2SO4. This correction is based upon the 
energy of formation of H2SO4 in solutions, such as will be 
present in the bomb at the end of a combustion. This energy 
is taken as -295.0 kJ/mol.^ A correction of 2 times 59.0 
kJ/mol of sulfur was applied in the ei correction, so the 
additional correction necessary is 295.0 - (2 times 59.0) = 
177 kJ/mol, or 5.52 kJ/per gram of sulfur in the sample (55.2 
J times weight of sample in grams times percent sulfur in 
sample). This causes ^2 to be 23.7 times weight of sample in 



grams times percent sulfur in sample. The factor 23.7 (equals 
55.2/2.326), for e^ (see 13.2) is to be used for calculating 
calorific value in British thermal units per pound. For other 
units, see Appendix X2. The values above are based on a 
coal containing about 5 % sulfur and about 5 % hydrogen. 
The assumption is also made that the H2SO4 is dissolved 
entirely in the water condensed during combustion of the 
sample. 

XI. 2.1 If a 1-g sample of such a fuel is burned, the 
resulting H2SO4 condensed with water formed on the walls 
of the bomb, will have a ratio of about 15 mol of water to 1 
mol of H2SO4. For this concentration, the energy of the 
reaction SO2 (gas) + V2 O2 + H2O (liquid) = H2SO4 (in 15 
moles of H2O) under the conditions of the bomb process is 
-295.0 kJ/moV^ Basing the calculation upon a sample of 
comparatively large sulfur content reduces the possible 
overall errors, because, for small percent of sulfur, the 
correction is smaller. 

XI. 3 Fuse (Ignition) Wire — Calculate the energy contrib- 
uted by burning the fuse wire in accordance with the 
directions furnished by the supplier of the wire. For example, 
the energy of the combustion of No. 34 B & S gage Chromel 
C wire is 6.0 J/mg or approximately 0.95 J/mm. For 
calculating ^2 for use in Eqs 2 and 3, these give ^2 = 0.41 
times length (mm) of wire or ^2 - 2.6 times weight (mg) of 
wire. The energy required to melt a platinum wire is constant 
for each experiment if the same amount of platinum wire is 
used. As the energy is small, its effect is essentially cancelled 
out in the relationship between the standardization experi- 
ments and the calorific value determinations, and it can be 
neglected. The factors listed above for ^2 (10.4.2 and 13.2) 
are suitable for calculating calorific value in British thermal 
units per pound. For other units, see Appendix X2. 



^ Calculated from data in National Bureau of Standards Technical Note 270-3. 
^ Calculated from data in National Bureau of Standards Circular 500. 



'^ Mott, R. A. and Parker, C, "Studies in Bomb Calorimetry IX — Formation 
of Sulfuric Acid," Fuel, Vol 37, 1958, p. 371. 



260 



# D2015 



X2. REPORTING RESULTS IN OTHER UNITS 



X2. 1 Reporting Results in Joules per Gram: 

X2. 1 . 1 The gross calorific value can be expressed in joules 
per gram, calories per gram, or British thermal units per 
pound. The relationships between these units are given in 
Table 1. 

X2.1.2 Because the energy of combustion of the reference 
material is measured and certified by the National Institute 
of Standards and Technology (NIST) in joules per gram, the 
most straightforward usage of the reference material would 
lead to the calorific value of the fuel in joules per gram. To 
carry out this procedure, make the changes outlined in 
X2.1.3 through X2.1.5. 

X2.1.3 For calculating energy equivalent, substitute Eq 
X2.1 forEq2: 

E=Wg)^e,']lt (X2.1) 

where the meanings of the symbols in Eq X2. 1 are the same 

as in Eq 2 except that: 

E' = energy equivalent in units of joules per tem- 

perature unit, 

H' = the heat of combustion of reference material 

in units of joules per gram weight in air (J/g 
from the certificate for the NIST benzoic 
acid), and 

^/ and ^3' = corrections in units of joules, (see Table 
X2.1). 
X2.1.4 For calculating gross calorific value, substitute 

Eq X2.2 for Eq 3: 

a(gross) = [fe')-^/-^2']/^ (X2.2) 

where the meanings of the symbols in Eq X2.2 are the same 
as in Eq 3 except that: 



Qy (gross) = gross calorific value with units of joules 

per gram (weight in air), 
E' = energy equivalent units, of joules per 

temperature unit, and 
^I'j e2\ and e^' = corrections in units of joules (see Table 
X2.1). 

X2.1.5 Precision: 

X2.1.5.1 Repeatability — Duplicate results by the same 
laboratory, using the same operator and equipment, should 
not be considered suspect unless they differ by more than 
120 J/g. 

X2. 1.5.2 Reproducibility — The results submitted by two 
or more laboratories (different equipment, operators, date of 
test, and different portions of the same sample) should not 
be considered suspect unless the results differ by more than 
240 J/g. 



TABLE X2.1 Alternative thermochemical Correction Factors 
(Units in Joules)"^ 



Correction 


Multlpiication 
Factor 


Multiply By 


ei'(HN03) . 


20 J/mL 


mL of 0.34 N NaaCOa 


63' (H2SO4) 


55.2 J/cgS 


percent of sulfur in sample times 
mass of sample in grams 


62 (fuse wire) 


0.95 J/mm 


lengtli (mm) of No. 34 B & S gage 


or ; 




Chromel C wire 


62' (fuse wire) 


1.14 J/mm 


length (mm) of No. 34 B & S gage iron 
wire 


62' (fuse wire) 
or 


6.0 J/mg 


mass (mg) of Chromel C wire 


e2' (fuse wire) 


7.4J/mg 


mass (mg) of Iron wire 



^ To be used in Eqs X2.1 and X2.2 only. 



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261